contracts: round-trip degraded provenance/watch-list/mode-changed; proto doc (Contracts-018,019)

src/ZB.MOM.WW.MxGateway.Contracts/Generated/MxaccessGateway.cs

@@ -668,8 +668,15 @@ namespace ZB.MOM.WW.MxGateway.Contracts.Proto {
   }
 
   /// <summary>
-  /// Provider selection / current provider for the alarm feed. UNSPECIFIED on a
-  /// SubscribeAlarmsCommand means auto: alarmmgr primary with subtag fallback.
+  /// Provider selection / current provider for the alarm feed. The zero value
+  /// has two distinct meanings depending on the use site:
+  ///   - As SubscribeAlarmsCommand.forced_mode, UNSPECIFIED means auto: alarmmgr
+  ///     primary with subtag fallback.
+  ///   - As a provenance value (OnAlarmTransitionEvent.source_provider,
+  ///     ActiveAlarmSnapshot.source_provider, OnAlarmProviderModeChangedEvent.mode,
+  ///     AlarmProviderStatus.mode), the worker always emits ALARMMGR or SUBTAG and
+  ///     never UNSPECIFIED; clients should treat a UNSPECIFIED provenance value as
+  ///     "unknown / not yet determined".
   /// </summary>
   public enum AlarmProviderMode {
     [pbr::OriginalName("ALARM_PROVIDER_MODE_UNSPECIFIED")] Unspecified = 0,
@@ -26528,6 +26535,12 @@ namespace ZB.MOM.WW.MxGateway.Contracts.Proto {
     /// <summary>Field number for the "degraded" field.</summary>
     public const int DegradedFieldNumber = 14;
     private bool degraded_;
+    /// <summary>
+    /// True when this snapshot came from the subtag-monitoring fallback rather
+    /// than the native alarmmgr provider — synthesized from data changes, reduced
+    /// fidelity (synthetic GUID, no native raise time). Mirrors
+    /// OnAlarmTransitionEvent.degraded.
+    /// </summary>
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
     public bool Degraded {
@@ -26540,6 +26553,11 @@ namespace ZB.MOM.WW.MxGateway.Contracts.Proto {
     /// <summary>Field number for the "source_provider" field.</summary>
     public const int SourceProviderFieldNumber = 15;
     private global::ZB.MOM.WW.MxGateway.Contracts.Proto.AlarmProviderMode sourceProvider_ = global::ZB.MOM.WW.MxGateway.Contracts.Proto.AlarmProviderMode.Unspecified;
+    /// <summary>
+    /// Which provider produced this snapshot. Mirrors
+    /// OnAlarmTransitionEvent.source_provider; always ALARMMGR or SUBTAG on the
+    /// wire (never UNSPECIFIED).
+    /// </summary>
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
     public global::ZB.MOM.WW.MxGateway.Contracts.Proto.AlarmProviderMode SourceProvider {